Radio transmission schemes, including frequency division duplexing (FDD) and time division duplexing (TDD), for mobile communication terminal devices such as mobile phones and smartphones are known. FDD employs two different frequency bands as a pair of a downlink signal and an uplink signal while TDD employs a downlink signal and an uplink signal in the same frequency band by time division.
A shared repeater system is also known in which service providers (carriers: communication service providers) share a repeater system (communication repeater system) for enabling use of mobile communication terminal devices in dead zones including indoors.
The FDD radio transmission requires a certain frequency interval (gap) between a downlink frequency band and an uplink frequency band. In recent years, the use of the TDD radio transmission scheme has been increasing due to tightness of available frequencies.
Thus, an increase in the number of devices by the TDD radio transmission scheme in the shared repeater system is expected.
In the shared repeater system adopting the TDD radio transmission, variations in time-division timing in adjacent bands among different service providers may cause mutual interference and deterioration in service quality or stop of service.
It is an object of the present invention to provide a communication repeater system and method which can reduce variations in time-division timing among different service providers and ensure improvements in service quality and continuity of service.